The rapid growth of the population has led to an increase in the emission of harmful gases into the environment. These toxic substances, including heavy metals, are disrupting the ecological balance and significantly raising environmental toxicity levels. To address these environmental challenges, various carbon nanomaterials—such as graphite, graphene, nanotubes, nanodiamonds, and carbon nanotubes (CNTs)—have been employed. Additionally, electrochemical sensors have been developed for the detection of environmental pollutants. Pure, mixed, and doped metal oxides (MOX) are utilized in the creation of electrical and electrochemical sensors due to their ability to perform online analysis and real-time identification. Carbon nanomaterials are among the most extensively researched due to their exceptional properties, including a high specific surface area, excellent carrier mobility, high electrical conductivity, flexibility, and optical transparency. The detection methods used in electrochemical sensors encompass a range of techniques, such as potential analysis, conductometry, and coulometry. Highly sensitive chemo-resistive sensors, based on doped variants of single semiconductors like ZnO, SnO2, WO3, TiO2, and Fe2O3, as well as multicomponent materials like BiFeO3, MgAl2O4, and SiTiO3, are employed to detect toxic gases (H2, CO, NO2) and volatile organic compounds (VOCs). The release of VOCs into the atmosphere has resulted in severe environmental issues, including pathogenic, mutagenic, and potentially fatal diseases.